1. Field of the Invention
The present invention generally relates to three-phase alternating current voltage regulators for balancing voltages on transmission lines between three-phase generators and loads, and more particularly to an automatically controlled three-phase alternating current voltage regulator.
2. Description of Related Art
Alternating current (AC) voltages generated from a three-phase generator are transmitted on transmission lines to various loads, such as electric motors. However, climatic conditions may result in fluctuation of the voltages in the transmission lines. If the loads receive the unstable voltages, they will operate unsteadily. Thus, it is necessary to balance the AC voltages in the transmission lines.
A microcomputer is typically used in a generator. Referring to FIG. 5, transmission lines 10 transmitting the alternating voltage generated from a three-phase generator 80 to a load 90 is depicted. A three-phase AC voltage regulator 999 is used for balancing the voltages in the transmission lines 10. The three-phase AC voltage regulator 999 includes a sampling circuit 20, a reference-voltage circuit 30, a microcomputer 40, an interface 50, and a compensator 70.
A line voltage is sampled from the transmission lines 10 by the sampling circuit 20. A line-to-line voltage is received from the transmission lines 10, and converted to a standard voltage by the reference-voltage circuit 30. The line voltage and the standard voltage are received, and compared by the microcomputer 40 to obtain a signal. The line voltage in the transmission lines 10 is compensated with the signal by the compensator 70. The microcomputer 40 is connected with a desktop computer via the interface 50 to monitor the three-phase AC voltage regulator 999.
However, the microcomputer is expensive, making the regulator also expensive.
Therefore, a three-phase AC voltage regulator is needed in the industry to address the aforementioned deficiency.